Some use disposable polyethylene body tents to prevent the cross contamination of DNA. I might consider using a body tent if it is raining to keep the rain from washing away evidence. Most of us have tents of different sizes to protect areas from the sun or rain, or to use for a staging area or command post.
We have lots of "reusable" tools for crime scenes. So the issue of cross contamination is one we must always consider. If we are considering DNA collection for a scene we must take precautions. For example, we might put on gloves and a one-use "Tyvek" suit. We might switch to one-use fingerprint brushes and individually packaged fingerprint powers.
If there is no need to collect DNA then we usually do not need to take such precautions.
Do SOCO's/CSI's use disposable body tents or reusable tents? I heard they use reusable but surely that could lead to a DNA contaminated scene?